service/dynamodb/api_op_GetItem.go

// Code generated by smithy-go-codegen DO NOT EDIT.

package dynamodb

import (
	"context"
	awsmiddleware "github.com/aws/aws-sdk-go-v2/aws/middleware"
	"github.com/aws/aws-sdk-go-v2/aws/signer/v4"
	"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
	"github.com/aws/smithy-go/middleware"
	smithyhttp "github.com/aws/smithy-go/transport/http"
)

// The GetItem operation returns a set of attributes for the item with the given
// primary key. If there is no matching item, GetItem does not return any data and
// there will be no Item element in the response. GetItem provides an eventually
// consistent read by default. If your application requires a strongly consistent
// read, set ConsistentRead to true. Although a strongly consistent read might take
// more time than an eventually consistent read, it always returns the last updated
// value.
func (c *Client) GetItem(ctx context.Context, params *GetItemInput, optFns ...func(*Options)) (*GetItemOutput, error) {
	if params == nil {
		params = &GetItemInput{}
	}

	result, metadata, err := c.invokeOperation(ctx, "GetItem", params, optFns, addOperationGetItemMiddlewares)
	if err != nil {
		return nil, err
	}

	out := result.(*GetItemOutput)
	out.ResultMetadata = metadata
	return out, nil
}

// Represents the input of a GetItem operation.
type GetItemInput struct {

	// A map of attribute names to AttributeValue objects, representing the primary key
	// of the item to retrieve. For the primary key, you must provide all of the
	// attributes. For example, with a simple primary key, you only need to provide a
	// value for the partition key. For a composite primary key, you must provide
	// values for both the partition key and the sort key.
	//
	// This member is required.
	Key map[string]types.AttributeValue

	// The name of the table containing the requested item.
	//
	// This member is required.
	TableName *string

	// This is a legacy parameter. Use ProjectionExpression instead. For more
	// information, see AttributesToGet
	// (https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LegacyConditionalParameters.AttributesToGet.html)
	// in the Amazon DynamoDB Developer Guide.
	AttributesToGet []string

	// Determines the read consistency model: If set to true, then the operation uses
	// strongly consistent reads; otherwise, the operation uses eventually consistent
	// reads.
	ConsistentRead *bool

	// One or more substitution tokens for attribute names in an expression. The
	// following are some use cases for using ExpressionAttributeNames:
	//
	// * To access an
	// attribute whose name conflicts with a DynamoDB reserved word.
	//
	// * To create a
	// placeholder for repeating occurrences of an attribute name in an expression.
	//
	// *
	// To prevent special characters in an attribute name from being misinterpreted in
	// an expression.
	//
	// Use the # character in an expression to dereference an attribute
	// name. For example, consider the following attribute name:
	//
	// * Percentile
	//
	// The
	// name of this attribute conflicts with a reserved word, so it cannot be used
	// directly in an expression. (For the complete list of reserved words, see
	// Reserved Words
	// (https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ReservedWords.html)
	// in the Amazon DynamoDB Developer Guide). To work around this, you could specify
	// the following for ExpressionAttributeNames:
	//
	// * {"#P":"Percentile"}
	//
	// You could
	// then use this substitution in an expression, as in this example:
	//
	// * #P =
	// :val
	//
	// Tokens that begin with the : character are expression attribute values,
	// which are placeholders for the actual value at runtime. For more information on
	// expression attribute names, see Specifying Item Attributes
	// (https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.AccessingItemAttributes.html)
	// in the Amazon DynamoDB Developer Guide.
	ExpressionAttributeNames map[string]string

	// A string that identifies one or more attributes to retrieve from the table.
	// These attributes can include scalars, sets, or elements of a JSON document. The
	// attributes in the expression must be separated by commas. If no attribute names
	// are specified, then all attributes are returned. If any of the requested
	// attributes are not found, they do not appear in the result. For more
	// information, see Specifying Item Attributes
	// (https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.AccessingItemAttributes.html)
	// in the Amazon DynamoDB Developer Guide.
	ProjectionExpression *string

	// Determines the level of detail about provisioned throughput consumption that is
	// returned in the response:
	//
	// * INDEXES - The response includes the aggregate
	// ConsumedCapacity for the operation, together with ConsumedCapacity for each
	// table and secondary index that was accessed. Note that some operations, such as
	// GetItem and BatchGetItem, do not access any indexes at all. In these cases,
	// specifying INDEXES will only return ConsumedCapacity information for
	// table(s).
	//
	// * TOTAL - The response includes only the aggregate ConsumedCapacity
	// for the operation.
	//
	// * NONE - No ConsumedCapacity details are included in the
	// response.
	ReturnConsumedCapacity types.ReturnConsumedCapacity
}

// Represents the output of a GetItem operation.
type GetItemOutput struct {

	// The capacity units consumed by the GetItem operation. The data returned includes
	// the total provisioned throughput consumed, along with statistics for the table
	// and any indexes involved in the operation. ConsumedCapacity is only returned if
	// the ReturnConsumedCapacity parameter was specified. For more information, see
	// Read/Write Capacity Mode
	// (https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ProvisionedThroughputIntro.html)
	// in the Amazon DynamoDB Developer Guide.
	ConsumedCapacity *types.ConsumedCapacity

	// A map of attribute names to AttributeValue objects, as specified by
	// ProjectionExpression.
	Item map[string]types.AttributeValue

	// Metadata pertaining to the operation's result.
	ResultMetadata middleware.Metadata
}

func addOperationGetItemMiddlewares(stack *middleware.Stack, options Options) (err error) {
	err = stack.Serialize.Add(&awsAwsjson10_serializeOpGetItem{}, middleware.After)
	if err != nil {
		return err
	}
	err = stack.Deserialize.Add(&awsAwsjson10_deserializeOpGetItem{}, middleware.After)
	if err != nil {
		return err
	}
	if err = addSetLoggerMiddleware(stack, options); err != nil {
		return err
	}
	if err = awsmiddleware.AddClientRequestIDMiddleware(stack); err != nil {
		return err
	}
	if err = smithyhttp.AddComputeContentLengthMiddleware(stack); err != nil {
		return err
	}
	if err = addResolveEndpointMiddleware(stack, options); err != nil {
		return err
	}
	if err = v4.AddComputePayloadSHA256Middleware(stack); err != nil {
		return err
	}
	if err = addRetryMiddlewares(stack, options); err != nil {
		return err
	}
	if err = addHTTPSignerV4Middleware(stack, options); err != nil {
		return err
	}
	if err = awsmiddleware.AddRawResponseToMetadata(stack); err != nil {
		return err
	}
	if err = awsmiddleware.AddRecordResponseTiming(stack); err != nil {
		return err
	}
	if err = addClientUserAgent(stack); err != nil {
		return err
	}
	if err = smithyhttp.AddErrorCloseResponseBodyMiddleware(stack); err != nil {
		return err
	}
	if err = smithyhttp.AddCloseResponseBodyMiddleware(stack); err != nil {
		return err
	}
	if err = addOpGetItemValidationMiddleware(stack); err != nil {
		return err
	}
	if err = stack.Initialize.Add(newServiceMetadataMiddleware_opGetItem(options.Region), middleware.Before); err != nil {
		return err
	}
	if err = addRequestIDRetrieverMiddleware(stack); err != nil {
		return err
	}
	if err = addResponseErrorMiddleware(stack); err != nil {
		return err
	}
	if err = addValidateResponseChecksum(stack, options); err != nil {
		return err
	}
	if err = addAcceptEncodingGzip(stack, options); err != nil {
		return err
	}
	if err = addRequestResponseLogging(stack, options); err != nil {
		return err
	}
	return nil
}

func newServiceMetadataMiddleware_opGetItem(region string) *awsmiddleware.RegisterServiceMetadata {
	return &awsmiddleware.RegisterServiceMetadata{
		Region:        region,
		ServiceID:     ServiceID,
		SigningName:   "dynamodb",
		OperationName: "GetItem",
	}
}